LG StudioWorks 520Si Owner's Manual page 26

NO POWER
CHECK C905
DC VOLTAGE?
DC=MORE THAN 130V
YES
CHECK
T901
PIN 4 ?
YES
CHECK
SMPS SECONDARY
DC VOLTAGE ?
6.3V, 14V,
55V, 76V
YES
CHECK
Q914 EMITTER
VOLTAGE (5V)?
YES
TROUBLE IN
OTHER PRIMARY CIRCUIT
1. NO POWER
NO
NO
CHECK
IC901?
YES
TROUBLE IN
D906, D907, R906
NO
NO
- 15 -
TROUBLE IN
F901, R901,
D901, D902, D903, D904
TROUBLE IN
NO
Q915, Q917, IC901,R902,
R914, D906, D907
TROUBLE IN
D921, D922, D924, D928
OR THEIR CONNECTED
COMPONENTS
TROUBLE IN
Q904, Q905, Q914
CIRCUIT